1. Field Of The Invention
This invention relates generally to a polishing tool for contact lenses and an associated method and more specifically, to a product and method that polishes the central optical section, the edges and the outside and peripheral bevels of a contact lens to very precise tolerances.
2. Description Of The Prior Art
Polishing a contact lens is necessary in order to achieve a proper fit between the contact lens and the eye. The more precisely and smoothly polished a contact lens is the sharper the image the wearer can obtain and the more comfortably the contact lens will fit the wearer.
The prior art contains polishing tools that have polishing heads mounted on a rigid base (usually brass) of an exact curve. It is important to have a rigid tool in order to implant its curve to the central optical portion of the contact lens in order to achieve good optical clarity.
Another aspect of contact lens fitting involves polishing the outside and peripheral bevels and the edges of a contact lens. In the periphery of the cornea, where the outer part of the contact lens fits, there is a flatenning of the corneal curve. This must be imitated by the inside periphery of the contact lens to provide for complementary configurations. It has been known in the art to employ a series of curved grinding balls to make these bevels, this variable surface then being polished with the same type rigid tools described above as were used in polishing central curves. This method, however, produced an uneven contact lens surface having a series of ridges in the junction or shoulder regions where the peripheral bevels and the central optical curves met.
U.S. Pat. No. 3,583,111, while not related to contact lenses, discloses a lens grinding apparatus comprising an abrasive disc fastened to a resilient cushion and a holder. The lens is placed on a rotating table and is brought in contact with the abrasive disc in order to polish the lens. The metal portion determines the shape of the polishing tool.
U.S. Pat. No. 3,517,466, which also does not relate to contact lenses, discloses a polishing wheel for contoured surfaces. Abrasive-faced studs are mounted on a stud carrying disc that is in turn mounted on a sponge rubber material. These layers are then mounted on a steel plate that engages a steel shaft.
U.S. Pat. No. 2,990,664 shows a method of finishing the edges of a contact lens. The lens is held on a lens holder, and the method involves twelve steps including beveling, touch polishing of the bevel, and creating the secondary curve.
U.S. Pat. No. 3,238,676 discloses various means for polishing the exterior of a contact lens by means of an enlarged concave surface.
Several patents disclose different types of grinding pads that can be used in association with a lens grinding tool. See, e.g., U.S. Pat. Nos. 3,144,737 and 3,578,850.
There remains a need for a contact lens polishing apparatus that polishes the interior surface, or central optical zone, the edges and the outside and peripheral bevels of a contact lens to a smooth blended predetermined curved shape. There also remains a need for a resilient polishing tool that can be easily manufactured into many different specific and exact curves so as to facilitate different central optical section curvatures and different edge and outside and peripheral bevel shapes.